c# - Debugging sparql function return values in dotNetRDF -

i have sparql query filter looks like:

select *  {     ...      data:person_1  app:maxdistance  ?value     data:person_1  app:coordinates  ?coord1     data:person_2  app:coordinates  ?coord2      filter (          xsd:float(strbefore(?value, " miles"))             >=          app:miles-between(?coord1, ?coord2)     ) }  

?value here literal in form "x miles" (x being numeric quantity)

so want filter out people farther away person_1's maxdistance, seems filter returns false , nobody ever filtered out.

the problem though i'm not sure how debug this. know return value of app:miles-between since it's custom c# function can breakpoint in , see correctly returns double value.

however don't know xsd:float() , strbefore return. there anyway bind return value variable , output select?

i tried using explainqueryprocessor doesn't give me enough information, such return values want know.

however don't know xsd:float() , strbefore return. there anyway bind return value variable , output select?

you want bind:

select ?floatvalue ?milesbetween {   …   bind( xsd:float(strbefore(?value, " miles")) ?floatvalue )   bind( app:miles-between(?coord1, ?coord2) ?milesbetween ) }